HP sneaks out printer firebomb firmware security fix

Says no one has blown up any LaserJets

HP has quietly patched a serious security vulnerability that had left its LaserJet printers open to attack by net villains.

The security bug, first discovered by researchers at Columbia University, created a means for miscreants to install malware on vulnerable devices simply by uploading new firmware to them over a network or tricking users into printing a specially constructed document that installs a malicious firmware update.

The flaw, which stemmed from a failure to ensure firmware updates are digitally signed, could allow hackers to extract files previously printed or scanned by compromised devices, or launch attacks from hacked gear against more sensitive machines from within a corporate network.

Some reports at the time speculated that the same vulnerability could even be used to turn compromised printers into firebombs, although built-in thermal controls are not affected by firmware updates (malicious of otherwise) and ought to prevent this.

HP quietly snuck out a fix for affected printers on 23 December, two days before Christmas, as part of a low-key update. A list of affected devices can be found on HP's website here.

Researchers at Columbia University demonstrated the flaw at the Chaos Computing Congress (28c3) hacker conference in Berlin late last month - a YouTube video is here. ®